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Lithium manganese-based composite oxide and method for preparing the same

a composite oxide and lithium manganese technology, applied in the direction of manganates/permanentates, cell components, cell component details, etc., can solve the problems of significant deterioration in battery performance, difficult to meet the increasing demand, and high material costs of lithium-ion batteries, so as to improve charge/discharge characteristics, adversely affecting charge/discharge characteristics, the effect of improving charge/discharge characteristics

Inactive Publication Date: 2007-09-20
NAT INST OF ADVANCED IND SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a novel material that can maintain a high discharge voltage of 3 V or more over long charge / discharge cycles, while also providing a higher discharge capacity than traditional positive electrode materials. This material can be prepared using lower-cost starting materials that are less limited in natural resources, and also exhibits improved charge / discharge characteristics compared to conventional low-cost materials. The invention is based on the discovery that a solid solution of lithium-iron-titanium-manganese-based oxide can be used as a positive electrode material in a lithium-ion battery, and that this material exhibits improved charge / discharge characteristics over traditional materials. The invention provides a method for preparing this material and a positive electrode material and lithium-ion battery that use this material.

Problems solved by technology

Lithium cobalt oxide, however, contains a large amount of the rare metal, cobalt, thus being a cause of the high material costs of lithium-ion batteries.
Further considering the fact that about 20% of cobalt resources are presently used in the battery industry, it seems to be difficult to meet the increasing demand only with positive electrode materials made of LiCoO2.
), causing significant deterioration in battery performance.
LiMnO2, therefore, has also not come into practical use.
However, lithium ferrite obtained by a general method, i.e., mixing sources of iron and lithium, and firing the mixture at high temperatures, hardly becomes charged and discharged, and hence cannot be used as a positive electrode material for lithium-ion batteries.
This material, however, has an average discharge voltage of 2.5 V or less, which is remarkably lower than the value of LiCoO2 (about 3.7 V), and is hence difficult to use as a substitute for LiCoO2.

Method used

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  • Lithium manganese-based composite oxide and method for preparing the same
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  • Lithium manganese-based composite oxide and method for preparing the same

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0096]To 500 mL of distilled water was added 40.40 g of an iron (III) nitrate nonahydrate, 19.79 g of a manganese (II) chloride tetrahydrate, and 40.00 g of a 30% aqueous titanium sulfate solution (total amount: 0.25 mol, Fe:Mn:Ti molar ratio: 1:1:0.5), and thoroughly dissolved. An aqueous lithium hydroxide solution (a solution of 50 g of a lithium hydroxide monohydrate dissolved in 500 mL of distilled water) was prepared in a separate beaker. After pouring this aqueous lithium hydroxide solution into a titanium beaker, 200 mL of ethanol was added and stirred. The lithium hydroxide solution was then allowed to stand in a thermostat at a constant temperature of −10° C. The aqueous solution of metal salts obtained above was then added dropwise into the aqueous lithium hydroxide solution over a period of 2 to 3 hours, thus forming a Fe—Mn—Ti precipitate. After confirming that the solution had been made completely alkaline (a pH of 11 or more), the solution containing the coprecipitate ...

example 2

[0115]As in Example 1, a coprecipitate was formed, hydrothermally treated and washed with water. The obtained powder was mixed with an aqueous lithium hydroxide solution of 5.25 g of a lithium hydroxide monohydrate dissolved in 100 mL of distilled water and stirred. The mixture was then dried at 100° C. overnight and pulverized to form a powder.

[0116]The powder was then heated in air to 650° C. over 1 hour. After firing at that temperature for 1 minute, the powder was cooled to about room temperature in a furnace, and then the fired product was washed with distilled water to remove excess lithium salts, filtered and dried to obtain the target iron- and titanium-containing Li2MnO3 as a powdery product.

[0117]The X-ray diffraction pattern of this product is shown in FIG. 7. According to a Rietveld analysis (using RIETAN-2000), all of the peaks were indexed by a crystal phase with a unit cell (R 3 m) of layered rock-salt type iron-containing Li2MnO3 (first phase: a=2.883(3) Å, c=14.239(...

example 3

[0132]To 500 mL of distilled water was added 35.35 g of an iron (III) nitrate nonahydrate, 17.32 g of a manganese (II) chloride tetrahydrate, and 60.00 g of a 30% aqueous titanium sulfate solution (total amount: 0.25 mol, Fe:Mn:Ti molar ratio: 0.7:0.7:0.6), and thoroughly dissolved. An aqueous lithium hydroxide solution (a solution of 50 g of a lithium hydroxide monohydrate dissolved in 500 mL of distilled water) was prepared in a separate beaker. After pouring this aqueous lithium hydroxide solution into a titanium beaker, 200 mL of ethanol was added and stirred. The lithium hydroxide solution was then allowed to stand in a thermostat at a constant temperature of −10° C. The aqueous solution of metal salts obtained above was then added dropwise into this aqueous lithium hydroxide solution over 2 to 3 hours, thus forming a Fe—Mn—Ti precipitate. After confirming that the solution had been made completely alkaline (a pH of 11 or more), the solution containing the coprecipitate was oxi...

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Abstract

The present invention provides a lithium manganese-based composite oxide represented by the compositional formula: Li1+x(Mnl-m-nFemTin)1-xO2, wherein 0<x<⅓, 0≦m≦0.75, 0.01≦n≦0.75, and 0.01≦m+n<1, and comprising a crystal phase of layered rock-salt type structure. The composite oxide is capable of maintaining an average discharge voltage of 3 V or more over long charge / discharge cycles. The composite oxide can be prepared using lower-cost starting materials, and exhibits improved charge / discharge characteristics over conventional low-cost positive electrode materials.

Description

BACKGROUND OF THE INVENTION[0001](1) Field of the Invention[0002]The present invention relates to lithium manganese-based composite oxides useful as positive electrode materials for next-generation, low-cost lithium-ion batteries, and a method for preparing such lithium manganese-based composite oxides.[0003](2) Description of the Related Art[0004]A majority of secondary batteries presently mounted in portable equipment such as cellular phones, notebook computers, etc., in Japan are lithium-ion batteries. Such lithium-ion batteries are also expected to become practical as large batteries for use in electric vehicles, electric load leveling systems, etc., and are therefore increasing in importance.[0005]A lithium-ion battery of today employs a lithium cobalt oxide (LiCoO2) as a typical positive electrode material, and a carbon material such as graphite as a negative electrode material.[0006]In such a lithium-ion battery, the amount of lithium ions that are reversibly deintercalated (...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H01M4/50H01M4/52C01G45/12C01G49/00H01M4/131H01M4/505H01M4/525H01M10/05
CPCC01G45/1228Y02T10/7011C01P2002/52C01P2002/72C01P2002/76C01P2002/77C01P2006/40H01M2/0222H01M4/131H01M4/382H01M4/505H01M4/525H01M4/623H01M4/625H01M10/052H01M2300/0025Y02E60/122C01G49/009Y02E60/10H01M50/109Y02T10/70
Inventor TABUCHI, MITSUHARUNABESHIMA, YOKOADO, KAZUAKITATSUMI, KUNIAKITAKEUCHI, TOMONARI
Owner NAT INST OF ADVANCED IND SCI & TECH